U.S. Pat. No. 6,289,552 discloses a vacuum cleaner including a housing having a nozzle that incorporates an agitator cavity. A rotary agitator is received in the agitator cavity. A light source is held in an illumination compartment carried on the housing. A first window divides the illumination compartment from the agitator cavity and a second window provides an outer facing for the illumination compartment. The light source illuminates the agitator which is viewed through the first and second windows.
U.S. Pat. No. 5,467,501 discloses a vacuum cleaner having a transparent belt view window formed in the vacuum cleaner hood to allow the operator to observe the operating condition of the belt therein, the belt being operable to transfer rotational motion from a motor output shaft to a rotary brush. The belt may include a pattern of markings allowing the user to distinguish between rotating and non-rotating operating conditions.